1. Field of the Invention
The invention generally relates to handovers in wireless communication environments, and more particularly, to apparatuses, systems, and methods for enhancing inbound handovers when multiple home base stations having the same physical cell identity (PCI) or physical scrambling code (PSC) are disposed in the coverage of a macro base station.
2. Description of the Related Art
In a typical wireless communication network, the deployment of network nodes is generally planned by the operator beforehand. The network coverage is sometimes inevitably limited due to signal attenuation in structures, especially in indoor areas, such as home premises and office areas. A femtocell is a small cellular base station, typically designed for use in a home or small business, which enhances reception quality of a wireless communication network in indoor coverage. Since a femtocell features enhancing reception quality of macro cell, the coverage of a femtocell is small and a femtocell is generally in the coverage of macro cell to amend the coverage hole of macro cell. In a hybrid access network, the coverage of a macro base station may consist of a large number of femtocells. FIG. 1 illustrates the network topology of such a hybrid access network. For the third generation partnership project (3GPP) long term evolution (LTE) network, a femtocell may be referred to as a home evolved Node-B (or HeNB), and a macro base station may be referred to as a macro evolved Node-B (MeNB). Generally, each base station, including each HeNB and MeNB, broadcasts a specific synchronization code to allow the user equipments (UE) to synchronize with the timing of the suitable base stations. This specific synchronization code can be further used for cell identification, and the synchronization code for the use of cell identification is referred to as a PCI. By utilizing the PCI, a UE may rapidly report to eNB to which HeNB with better reception quality is suitable to camp on.
However, the number of the cell identifications is limited in a wireless communications network. For example, the maximum number of PCIs in an LTE network is 504. In a densely-deployed environment, such as metropolitan area, the number of HeNBs in the coverage of an MeNB may be larger than the maximum number of PCIs defined for the LTE networks, and so, it is very likely that multiple HeNBs located in the coverage of one MeNB would have the same PCI. When an MeNB requests a UE to report the detected cells, PCI confusion may occur, in which the MeNB may not be able to recognize which HeNB the UE reported. When the number of HeNBs grows in the coverage of an MeNB, the PCI confusion gets serious and further causes a major burden for the handovers from the MeNB to one of the HeNBs (usually referred to as inbound handovers), e.g. data forwarding to multiple candidate HeNBs to prevent handover failure. Thus, it is desirable to address the PCI confusion and provide inbound handovers with low complexity, e.g. reducing the number of candidate HeNB to one.